what kind of gecko? incubation temps and time vary by gecko. for leos and cresteds i use a shoebox size rubbermaid with about 2-3 inches of moist perlite in it. cresteds incubate at room temp but leos need heat, which i supply via heat tape (under the box) hooked up to a thermostat.
incubate at 78-90 degrees. leos are temp sex dependent, so lower incubation temps will give you females, higher will be males. mid-range temps give a mix of both. incubation times vary up to about 60 days--warmer temps result in less incubation time. also, when removing eggs from the laying site, make sure not to turn them, and to keep them in the same position when you put them in the incubator. good luck to your friend!